Investigations into alleged misconduct by prison staff have risen by a third in a year, figures have revealed.
More than 2,500 charges were investigated in 2018-19, up from 1,894 the previous year.
Alleged "breach of security" - which can include bringing contraband into jails - and use of "unnecessary" force contributed to the rise.
The Prison Service said action was taken against the "small minority that engaged in inappropriate behaviour".
Mick Pimblett, assistant general secretary of the Prison Officers Association (POA), blamed some of the rises on inexperienced staff and a lack of training.
There were 2,511 investigations into alleged misconduct by 1,286 prison staff in England and Wales in 2018-19, according to figures obtained by BBC Radio Kent.
Prior to that the number of investigations had been falling.
In the same time, 529 staff were disciplined, with 112 recommended for dismissal.
Nearly 500 investigations into allegations of "breach of security" in prisons took place in the year ending March 2019.
The charge covers a "wide range of disciplinary offences", which can include anything from leaving an internal gate unlocked to "conveying unauthorised articles into a prison", Mr Pimblett said.
In the same year there were 169 investigations launched into alleged assaults and unnecessary use of force on prisoners.
'Unreasonable to roll on floor'
Mr Pimblett said use of force generally had increased since 2014 "due to the violent workplace prison officers have to work in".
The Prison Service "appears reluctant" to provide personal protective equipment - such as pepper spray - that "would prevent any accusations of unnecessary force", he said.
"In this day and age it is unreasonable to expect prison officers to roll around on the floor with prisoners," he said.
Dave Cook, a member of the POA's executive council who works at a prison in Kent, said the figures did not show how many allegations were proven and represented "a very small number of corrupt staff, or wrongdoing staff".
Peter Dawson, director of the Prison Reform Trust, said the rise in investigations may "provide reassurance that people feel able to speak out, and that when staff are found to have acted inappropriately their misconduct will be formally challenged".
However, he said it was unclear if the rise in allegations was the result of "declining standards of conduct" or an increase in people reporting misconduct.
The figures cover 105 prisons across England and Wales, excluding the 14 institutions run by private companies.
A spokeswoman for the Prison Service said: "The overwhelming majority of our prison staff are dedicated and honest, but the small minority that engage in inappropriate behaviour are investigated and suitable action is taken.
"Last year, the government announced £100m to improve prison security, including increased funding for our counter corruption unit, which roots out the small minority of dishonest staff and the criminals who seek to manipulate them."